Yes, I had come to the same conclusions as you seem to have done. There are some notes on the HDS site that indicate (in rather tortured English) more or less what the BackBlaze
comment says (which I had not seen, so thanks for the link).
I think I may have deduced what those two SMART charts mean:
- The SER (Seek Error Rate): the chart seems to be a graph over time showing when a Seek Error occurred and what the accumulated seek counter stood at, at that point.
- The RRER (Raw Read Error Rate): the chart seems to be a graph over time showing when a Raw Read Error occurred and what the incremental read counter (reads since last error) stood at, at that point.
Thus, we have, after an extended period of apparently improving stability/reliability (reducing frequency of errors), a second
Seek/Raw Read error occurring on 2015-03-20 relatively soon after the last/preceding error, and then a third occurring relatively soon after the second.
We probably won't be able to establish what caused the errors, but I shall examine the Windows Events logs to see if anything shows there. However, we can see from the CHKDSK output (run after the SMART S/RR errors were charted) that CHKDSK:
- corrected orphaned file errors, and found some unindexed files, in Stage 2.
- corrected free space marked as allocated in the MFT, in Stage 3.
- corrected free space marked as allocated in the volume bitmap, in Stage 3.
I don't know much about these things, but I would suppose that, if further S/RR errors occur within a short period, then there may be a problem causing
reducing stability/reliability (i.e., increasing frequency of errors). Otherwise, the errors may be an improbable statistical coincidence, or the CHKDSK operation may have fixed something that could have been a causal problem of the errors, in (say) the file structure.
So, it's probably a case of "wait and see".
Yesterday I downloaded, installed and ran Seagate's proprietary SeaTools
software to check this (Seagate) disk, and it checked out with no problems on an "extended test" run - and Seagate's own instructions are that if it passes that test then there is unlikely to be anything wrong with the disk.
I wouldn't have known about any of this at all if I had not had the HDS information charts showing the disk health status and
the SE/RRE counters' data from that particular disk.